1. Field of the Invention
This invention relates to computer-aided drafting systems and particularly to storing sequences of system commands that can later be automatically retrieved and executed. It also relates particularly to automatically supplying parameters for drawings to maintain predetermined relationships between independent and dependent geometrics (entities in a drawing such as a cam, gear, lever, or the like).
2. Description of Related Art
The term "macro" is a short form for macroinstruction, a term from the computer programming art denoting a sequence of instructions for performing a predetermined function. In computer assembler programs, a macro can be defined and then inserted any place in the program by placing the name of the macro where the sequence of instructions is to be placed. This precludes having to write the sequence each time it is to be used, a useful feature where a function is to be performed many times. It reduces the possibility of errors and has the advantage over using subroutines of being faster because there is no need to call the subroutine, to supply any needed data, and to transfer back to the calling program.
In the CAD (computer-aided drafting) art, certain graphics (images) are supplied in libraries included with the program, especially for use in specialized fields. Often, however, the user has to supply unique graphics, symbols, icons, or the like that are not available in the library. Most systems supply the ability to design and to store user-designed graphics which can then be copied out of the library onto a drawing the same way as the prestored graphics.
Another way of enabling the user to supply his own graphics is to permit the user to store a macro to be called by the user when the graphic is needed. The graphic is designed by executing a series of commands supplied by the system manufacturer, for example, by combining standard shapes such as circles, boxes, and the like.
Present systems having the macro capability require the user to learn and to use a complicated macro language. This often leads to inefficient macros and the need for many corrections in the construction of the macro.
If a group of images depends on certain parameters to maintain a given relationship amongst the images, e.g., the ratio of a driven gear to a driving gear when the driving gear dimensions are supplied at execution time, the only way in the prior art to draw the images is for the user to do the calculations and supply the parameters for all the images each time the group is drawn.
In the prior art, U.S. Pat. No. 4,622,546 shows the use of macroinstructions for supplying display characters. Each character in a set of stored characters has an address that points to an associated macroinstruction and bit map. The macroinstructions contains executable instructions that establish the size and location of its corresponding bit map. There is no disclosure, however, of a method whereby a user can create a macroinstruction.
U.S. Pat. No. 4,439,761 teaches a technique for coupling a processor to a display device which is independently controlled. The source transmits instructions that describe a character to be displayed and the independent control in the display device interprets the received drawing instructions into a particular bit pattern tailored to the characteristics of the display device. The instructions are fixed and no method for permitting the user to create instructions is disclosed.
U.S. Pat. No. 4,710,885 discloses the use of a special tag in a procedural language that causes a graphic figure to be included on the output together with text.
U.S. Pat. No. 4,656,603 discloses the use of patterns or icons having a set of instructions associated therewith. A user can select and combine the icons to create more complicated icons. Icons and functions can be combined on a drawing.
None of these prior art patents, however, show or suggest the invention claimed herein.